线程对于共享资源不安全,线程拥有各自的栈空间.
主动终止: return pthread_eixt()参数通用指针
被动终止: pthread_cancle(pthid);同一个进程的其他线程
exit(0) _exit(0) 进程终止
pthread_join(pthread_t th_id,void **thread_return);
阻塞 ,等待子线程结束,并且释放资源
参数2 等待线程返回值( return(0) pthread_exit(0)
#include<stdlib.h>
#include <pthread.h>
#include <stdio.h>
#include <math.h>
typedef struct
{
char name[20];
int time;
int start;
int end;
}ReacArg;
//线程函数
void* th_fn(void *arg)
{
ReacArg *r = (ReacArg*)arg;
int i=r->start;
for(;i<=r->end;i++)
{
printf("%s(%lx) run %d
",r->name,pthread_self(),i);
usleep(r->time);//微妙
}
return (void*)0;
}
int main()
{
int err ;
//创建创建线程rabbit
pthread_t rabbit ,turtle;
ReacArg r_a={"rabbit",(int)(drand48()*100000),20,50};
ReacArg t_a={"turtle",(int)(drand48()*1000),20,50};
if((err = pthread_create(&rabbit,NULL,th_fn,(void*)&r_a))!=0)
{
perror("pthread_create error");
}
//创建线程turtle 第四个参数 结构体
if((err = pthread_create(&turtle,NULL,th_fn,(void*)&t_a))!=0)
{
perror("pthread_create error");
}
pthread_join(rabbit,NULL);
pthread_join(turtle,NULL);
printf("contrl thread id: %lx",pthread_self());
printf("finished
");
return 0;
}
#include<stdlib.h>
#include <pthread.h>
#include <stdio.h>
typedef struct
{
int d1;
int d2;
}Arg;
void *th_fn(void* arg)
{
Arg *r = (Arg*)arg;
return (void*)r;
}
int main(void)
{
int err;
//int *result; //接受返回值
pthread_t th;
printf("%lx
",sizeof(enum type));
Arg r={30,50};
if((err = pthread_create(&th,NULL,th_fn,(void*)&r))!=0)
{
perror("create erro
");
}
// pthread_join(th,(void**)&result);
// printf("获得结果:%d
",((Arg*)result)->d1);
int re;
pthread_join(th,(void*)&re);
printf("获得结果:%d
",((Arg*)re)->d1);
return 0;
}
//定义结构体(多个对象需要同样的处理) 开启线程(处理) 返回结果
主要用到的函数：
sem_t sem;
int sem_init(sem_t *sem, int pshared, unsigned int value);，其中sem是要初始化的信号量，pshared表示此信号量是在进程间共享还是线程间共享，value是信号量的初始值。
int sem_destroy(sem_t *sem);,其中sem是要销毁的信号量。只有用sem_init初始化的信号量才能用sem_destroy销毁。
int sem_wait(sem_t *sem);等待信号量，如果信号量的值大于0,将信号量的值减1,立即返回。如果信号量的值为0,则线程阻塞。相当于P操作。成功返回0,失败返回-1。
int sem_post(sem_t *sem); 释放信号量，让信号量的值加1。相当于V操作。
#include <pthread.h>
#include <semaphore.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
将信号量定义为全局变量，方便多个线程共享
sem_t sem;
void * get_service(void *thread_id)
{
int customer_id = *((int *)thread_id);
if(sem_wait(&sem) == 0) {
usleep(100); service time: 100ms
printf("customer %d receive service ...id:%ld
", customer_id,getpid());
printf("l%d
",pthread_self());
sem_post(&sem);
}
}
#define CUSTOMER_NUM 10
int main(int argc, char *argv[])
{
初始化信号量，初始值为2，表示有两个顾客可以同时接收服务
sem_init(&sem, 0, 2);
pthread_t customers[CUSTOMER_NUM];
int i, ret;
for(i = 0; i < CUSTOMER_NUM; i++){
int customer_id = i;
ret = pthread_create(&customers[i], NULL, get_service, &customer_id);
if(ret != 0){
perror("pthread_create");
exit(1);
}
else {
printf("Customer %d arrived.
", i);
}
usleep(10);
}
int j;
for(j = 0; j < CUSTOMER_NUM; j++) {
pthread_join(customers[j], NULL);
}
sem_destroy(&sem);
return 0;
}
*/